Asthma

New Zealand has high asthma rates in children compared with other countries

New Zealand has a high prevalence rate of asthma in children than other countries [1–2]. A small number of children die from asthma each year; in 2018, five children died from asthma in New Zealand [3].

Asthma affects a person’s airways and makes it difficult to breathe. Poor indoor environment conditions have been identified to be associated with the increased risk of developing asthma in children. Second-hand smoke exposure can increase the risk of having asthma and wheeze in children [4–6] Indoor dampness/mould is also associated with asthma onset and exacerbation in children [7–9]. Additionally, several studies have found an increase in asthma prevalence or incidence associated with exposure to nitrogen dioxide [10] and transport-related air pollution [11]. Asthma exacerbations can also be triggered by lower respiratory tract infections [12].

The COVID-19 pandemic

In March 2020, the New Zealand Government pursued an elimination strategy for COVID-19. New Zealand moved to Alert Level 4 (Lockdown) on 25 March 2020, along with temporary border closures, quarantine requirements, community testing, school closures, and contact tracing. These public health measures appeared to have affected asthma hospitalisation rates in children aged 0–14 years in 2020 and 2021.

Asthma hospitalisations are on the rise again after a drop in 2020

In 2021, there were 6027 hospitalisations in children aged 0–14 years, a 56% increase since 2020 (3872 hospitalisations) (Figure 1). This drop coincided with the nationwide COVID-19 lockdown on 25 March 2020. However, as COVID-19 restrictions have eased over time, the number of hospitalisations has almost bounced back to pre-COVID-19 levels. 

 Figure 1: Number of asthma hospitalisations in children aged 0-14 years, 2001-21

Information about the data

Asthma hospitalisations

Source: National Minimum Dataset, Ministry of Health

Definition: Acute and semi-acute hospitalisations with asthma (ICD-10AM J45–J46) or wheeze (R06.2) as the primary diagnosis, for children aged 0–14 years.

Asthma prevalence

Source: New Zealand Health Survey, Ministry of Health

Definition: Children aged 2–14 years who have been diagnosed by a doctor as having asthma, and who currently take medication (inhalers, medicine, tablets, pills or other medication) for it.  

References

1. Lai CKW, Beasley R, Crane J, Foliaki S, Shah J, Weiland S. 2009. Global variation in the prevalence and severity of asthma symptoms: Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC). Thorax 64: 476–483. 

2. OECD. 2015. CO1.6: Disease-based indicators: prevalence of diabetes and asthma among children. OECD Family Database. Available online: https://www.oecd.org/els/family/CO_1_6_Diabetes_Asthma_Children.pdf  (accessed 30/10/2017).

3. Ministry of Health. 2021a. Mortality web tool:  Mortality and Demographic Data - series. Wellington: Ministry of Health. URL: https://www.health.govt.nz/nz-health-statistics/health-statistics-and-data-sets/mortality-and-demographic-data-series  (Accessed 04/10/2021).

4. He Z, Wu H, Zhang S, et al. 2020. The association between secondhand smoke and childhood asthma: A systematic review and meta‐analysis. Pediatric Pulmonology 55(10): 2518-2531.

5. Hollenbach JP, Schifano ED, Hammel C, et al. 2017. Exposure to secondhand smoke and asthma severity among children in Connecticut. PloS ONE 12(3): e0174541.

6. U.S. Department of Health and Human Services. 2007. Children and Secondhand Smoke Exposure. Excerpts from The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

7. Caillaud D, Leynaert B, Keirsbulck M, et al. 2018. Indoor mould exposure, asthma and rhinitis: findings from systematic reviews and recent longitudinal studies. European Respiratory Review 27(148).

8. Jaakkola MS, Haverinen-Shaughnessy U, Douwes J, Nevalainen A. 2011. Indoor dampness and mould problems in homes and asthma onset in children. In M. Braubach, D.E. Jacobs & D. Ormandy (Eds.), Environmental burden of disease associated with inadequate housing: A method guide to the quantification of health effects of selected housing risks in the WHO European Region (pp. 5–31). Copenhagen: World Health Organization Regional Office for Europe. 

9. Prezant B, Douwes J. 2011. Calculating the burden of disease attributable to indoor dampness in New Zealand: Technical Report. Wellington: Centre for Public Health Research.

10. Guarnieri M, Balmes JR. 2014. Outdoor air pollution and asthma. Lancet 383(9928): 1581–1592.

11. Orellano P, Quaranta N, Reynoso J, Balbi B, Vasquez J. 2017. Effect of outdoor air pollution on asthma exacerbations in children and adults: Systematic review and multilevel meta-analysis. PLoS ONE 12(3): e0174050.

12. Homaira N, Hu N, Owens L, et al. 2022. Impact of lockdowns on paediatric asthma hospital presentations over three waves of COVID-19 pandemic. Allergy, Asthma & Clinical Immunology 18 (53): 1–6.